Acids fumaric

Fumaric acid is also used as a food additive at concentrations up to 3600 ppm, and as a therapeutic agent in the treatment of psoriasis and other skin disorders.  

Allomaleic acid allomalenic acid boletic acid butenedioic acid E297 1,2-ethenedicarboxylic acid lichenic acid trans-butenedioic acid NSC-2752 traMs-l,2-ethylenedicarboxylic acid U-1149 USAF EK-P-583. 

Fumaric acid occurs as white, odorless or nearly odorless, granules or as a crystalline powder that is virtually nonhygro-scopic. 

Acidulant antioxidant flavoring agent therapeutic agent. 

Fumaric acid is used primarily in liquid pharmaceutical preparations as an acidulant and flavoring agent. Fumaric acid may be included as the acid part of effervescent tablet formulations, although this use is limited as the compound has an extremely low solubility in water. It is also used as a chelating agent which exhibits synergism when used in combination with other true antioxidants. 

Fumaric acid is not permitted under UK or EU legislation for direct use in soft drinks, although it is permitted under Annex IV of Directive 95/2/EC (modified by directive 98/72/EC), with strict limits, in instant powders for fruit-, tea- or herbal-based drinks. Fumaric acid finds wide use in other countries as an acidulant, notably in the US market, where it has GRAS ( Generally Recommended As Safe ) status. Fumaric acid is currently manufactured in the United States via the acid-catalysed isomerisation of maleic acid. In terms of equivalent palate acidity it can be used at lower levels than citiic acid and typical replacement is suggested at two parts fumaric acid per three parts citric acid in water, sugar water and carbonated sugar water. 

The main drawback in the use of fumaric acid is its slow solubility rate in compar ison with citric acid, and special methods need to be employed in its dissolution. It has been claimed that fumaric acid and its salts have a tendency to stabilise the suspended matter in both flash-pasteurised and frozen fruit concentrates (McColloch Gentile, 1958). 

Fumaric acid would then appear to be a stronger acid in food and as a result of this, less fumaric acid would be required to achieve a specific level of tartness compared to other food acids. It is known to improve the quality of food and beverages and may also reduce the cost of such products. Fumaric acid may also be used in animal feed. Since 1946 fumaric 

Fumaric acid (pKi = 3.00 pK2 = 4.52) increases the shelf life of some dehydrated food products (e. g. pudding and jelly powders). It is also used to lower the pH, usually together with food preservatives (e. g. benzoic acid), and as an additive promoting gel setting. Fumaric acid is synthesized via maleic acid anhydride which is obtained by catalytic oxidation of butene or benzene (cf. Reaction 8.23) or is produced from molasses by fermentation using Rhizopus spp. 

Maleic acid 7 which is c/5-butene-2-dioic acid can be isomerized to its trans derivative, namely, fumaric acid 8, using a variety of techniques. 

After the primary recovery of MA during production, the remaining MA is recovered as maleic acid by scrubbing with water. Some of this can be and often is converted to fumaric acid. High-purity fumaric acid for food applications is made from refined MA. The isomerization may be brought about in a number of ways, e.g., thermal, yy (7i,83) catalytic. Aqueous solutions containing 40% maleic acid when heated to form fumaric 

Nearly 5% of MA produced in 1978 was converted to fumaric acid. The latter is used in paper sizing resins, specialty unsaturated polyesters, as a food acidulant, and flavoring agent. It has been cleared for use as a special dietary and nutritional additive and in some indirect applications such as the packaging of food.  

It may be added here that isomerization of other MA derivatives can also be brought about by a variety of reagents. This isomerization lends itself to custom designing resins such as unsaturated polyesters by modifying glass-transition temperatures. (See Chapter 12.) 

In Table 1.7, miscellaneous uses include alkyl resins, which are surfacecoating resins used in paints, varnishes, inks, adhesives, etc. This use accounted for a significant share of MA production in the past however, its contribution has declined considerably recently. 

In a 5-I. flat-bottom flask, equipped with a condenser (Note 1), a separatory funnel and a mechanical stirrer (Note 2), are placed 450 g. (2.24 moles) of sodium chlorate, 2 g. of vanadium pentoxide (Note 3) and 1 1. of water. The mixture is heated (Note 4) to 70-750 by supporting the flask to cm. above an electric hot plate. To the well-stirred solution is then added 200 g. (2.06 moles) of furfural (Note 5) over a period of seventy to eighty minutes. After the addition of furfural is complete, the mixture is heated at 70-75°, with stirring, for ten to eleven hours, and then allowed to stand at room temperature overnight. The mixture is filtered by suction, and the crude fumaric acid is dried in the air. The yield is 155-170 g. (65-72 per cent of the theoretical amount) (Note 6). 

More fumaric acid may be obtained from the filtrate by heating it on the water bath with 50 cc. of concentrated hydrochloric acid the solution usually turns blue at the end of the reaction. The solution is concentrated to about 700 cc. and then cooled with running water. The fumaric acid which separates is collected on a filter and dried in the air. The yield is 10-15 g. of a product which melts at 282 -284° in a sealed tube. 

The crude product is purified by recrystalIi2ation from about 1250 cc. of 1 N hydrochloric acid. This gives 100-110 g. of pure fumaric acid melting at 282-284° in a scaled tube. An additional amount of fumaric acid may be obtained by concentrating the filtrate to a small volume on a water bath. 

The total yield of pure fumaric acid is 120-138 g. (50-58 per cent of the theoretical amount). 

The condenser should be 80-90 cm. (32-36 in.) long and fitted with a wide inner tube. 

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Colourless prisms m.p. 130 C. Manufactured by treating maleic anhydride with water. It is converted to the anhydride by heating at By prolonged heating at 150 "C or by heating with water under pressure at 200 C, it is converted to the isomeric (trans) fumaric acid. Reduced by hydrogen to succinic acid. Oxidized by alkaline solutions of potassium permanganate to mesotartaric acid. When heated with solutions of sodium hydroxide at 100 C, sodium( )-malate is formed. Used in the preparation of ( )-malic acid and in some polymer formulations. 

Racemic acid, ( )-tartaric acid, is a compound of the two active forms. M.p. 273 C (with IHjO), m.p. 205°C (anhydrous). Less soluble in water than (-t-)-tartaric acid. Formed, together with mesotartaric acid, by boiling (4-)-tartaric acid with 30% NaOH solution, or by oxidation of fumaric acid. Potassium hydrogen racemate is very insoluble. 

Upon heating with hydrochloric acid, maleic acid, m.p. 144°, is converted into fumaric acid, m.p. 287° ... 

Both acids 3deld succinic acid, m.p. 185°, upon catalytic reduction (see Section 111,150), thus establishing their structures. Maleic and fumaric acids are examples of compounds exhibiting cis-trans isomerism (or geometric isomerism). Maleic acid has the cm structure since inter alia it readily 3delds the anhydride (compare Section 111,93). Fumaric acid possesses the trans structure it does not form an anhydride, but when heated to a high temperature gives maleic anhydride. 

Fumaric acid is conveniently prepared by the oxidation of the inexpensive furfural with sodium chlorate in the presence of a vanadium pentoxide catalyst ... 

B. Conversion of maleic acid into fumaric acid. Dissolve 10 g. of maleic acid in 10 ml. of warm water, add 20 ml. of concentrated hydrochloric acid and reflux gently (provide the flask with a reflux condenser) for 30 minutes. Crystals of fumaric acid soon crystaUise out from the hot solution. Allow to cool, filter oflF the fumaric acid, and recrystallise it from hot. A -hydrochloric acid. The m.p. in a sealed capillary tube is 286-287°. 

C. Fumaric acid from furfural. Place in a 1-litre three-necked flask, fitted with a reflux condenser, a mechanical stirrer and a thermometer, 112 5 g. of sodium chlorate, 250 ml. of water and 0 -5 g. of vanadium pentoxide catalyst (1), Set the stirrer in motion, heat the flask on an asbestos-centred wire gauze to 70-75°, and add 4 ml. of 50 g. (43 ml.) of technical furfural. As soon as the vigorous reaction commences (2) bvi not before, add the remainder of the furfural through a dropping funnel, inserted into the top of the condenser by means of a grooved cork, at such a rate that the vigorous reaction is maintained (25-30 minutes). Then heat the reaction mixture at 70-75° for 5-6 hours (3) and allow to stand overnight at the laboratory temperature. Filter the crystalline fumaric acid with suction, and wash it with a little cold water (4). Recrystallise the crude fumaric acid from about 300 ml. of iif-hydrochloric acid, and dry the crystals (26 g.) at 100°. The m.p. in a sealed capillary tube is 282-284°. A further recrystaUisation raises the m.p. to 286-287°. 

A small quantity (ca. 3 g.) of fumaric acid may be recovered from the 6ltrate by heating it on a water bath with 15 ml. of concentrated hydrochloric acid, evaporating to about 150 ml., and then cooling with running water. The fumaric acid which separates is recrystallised from N-hydrochloric acid. 

Crotonic acid exists in cis and trans forms (compare maleie and fumaric acids) CH3—C—H CH3—C—H... 

The diethyl fumarate is readily prepared as follows. Reflux a mixture of 146 g. of fumaric acid (Section 111,143), 185 g. (236 ml.) of absolute ethanol, 450 ml. of boizene and 20 g. of concentrated sulphuric acid for 12 hours. Pour into a large volume of water, separate the benzene layer, wash successively with water, saturated lodium bicarbonate solution and water, dry with anhydrous magnesium sulphate, and remove the solvent on a steam bath. Distil the residue and collect the diethyl fumarate at 213-215° the yield is 150 g. 

Supplement II, 2nd 1929 152-194 Oxalic acid, 502. Succinic acid, 601. Fumaric acid, 737... 

The biological dehydrogenation of succinic acid described in Section 5 8 is 100% stereoselective Only fumaric acid which has a trans double bond is formed High levels of stereoselectivity are characteristic of enzyme catalyzed reactions... 

Optically inactive starting materials can give optically active products only if they are treated with an optically active reagent or if the reaction is catalyzed by an optically active substance The best examples are found m biochemical processes Most bio chemical reactions are catalyzed by enzymes Enzymes are chiral and enantiomerically homogeneous they provide an asymmetric environment m which chemical reaction can take place Ordinarily enzyme catalyzed reactions occur with such a high level of stereo selectivity that one enantiomer of a substance is formed exclusively even when the sub strate is achiral The enzyme fumarase for example catalyzes hydration of the double bond of fumaric acid to malic acid m apples and other fruits Only the S enantiomer of malic acid is formed m this reaction... 

The reaction is reversible and its stereochemical requirements are so pronounced that neither the cis isomer of fumaric acid (maleic acid) nor the R enantiomer of malic acid can serve as a substrate for the fumarase catalyzed hydration-dehydration equilibrium... 

Unsaturated Polyesters. Unsaturated polyesters are produced by reaction between two types of dibasic acids, one of which is unsaturated, and an alcohol to produce an ester. Double bonds in the body of the unsaturated dibasic acid are obtained by using maleic anhydride or fumaric acid. 

Description of Method. Salt substitutes, which are used in place of table salt for individuals on a low-sodium diet, contain KCI. Depending on the brand, fumaric acid, calcium hydrogen phosphate, or potassium tartrate also may be present. Typically, the concentration of sodium in a salt substitute is about 100 ppm. The concentration of sodium is easily determined by flame atomic emission. Because it is difficult to match the matrix of the standards to that of the sample, the analysis is accomplished by the method of standard additions. 

TALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15)... 

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